If $x \triangleleft y = 3y+4$ and $x \boxdot y = xy+4x-y$, find $6 \triangleleft (2 \boxdot -2)$.
Answer: First, find $2 \boxdot -2$ $ 2 \boxdot -2 = (2)(-2)+(4)(2)-(-2)$ $ \hphantom{2 \boxdot -2} = 6$ Now, find $6 \triangleleft 6$ $ 6 \triangleleft 6 = (3)(6)+4$ $ \hphantom{6 \triangleleft 6} = 22$.